Features of nosocomial Klebsiella pneumoniae population

Aim. To determine the prevalence of resistant and dormant forms of Klebsiella pneumoniae in pediatric patients.

Materials and Methods. The study was conducted in the Regional Pediatric Clinical Hospital from 2013 to 2018. Antibiotic resistance of Klebsiella pneumoniae strains (n = 485) was studied by the disk diffusion test and using serial dilutions to identify minimum inhibitory concentration (Vitek 2 Compact). RAPD-typing of 34 Klebsiella pneumoniae was performed using the Total Lab program. In addition, we studied susceptibility of 42 and 76 Klebsiella pneumoniae strains to antiseptics and disinfectants, respectively. Sensitivity of 24 Klebsiella pneumoniae strains to 4 series of bacteriophages was measured using the Appelman method. Persistence of 39 of Klebsiella pneumoniae clinical isolates was carried out by Kaldalu method.

Results. Klebsiella pneumoniae was most frequently found in the intestines (826.41 per 1000 patients, 95% Cl = 80.24-84.80) and the throat (33.96 per 1000, 95% Cl = 2.38-4.56). Colonization of multiple loci was identified in 18.22 per 1000 patients (95% Cl = 4.42-7.22). The dominant circulation of clonal line A was established. The vast majority of Klebsiella pneumoniae strains (92.76%) were ampicillin-resistant. The minimal proportion of resistant strains was found for carbapenems, being 3.41% for imipenem and 4.25% for meropenem. One third of the strains (31.22%) were resistant to amoxicillin combined with clavulanic acid, and 34.90% of the strains produced extended-spectrum P-lactamase. The share of resistant strains to third-generation cephalosporins (cefotaxime and ceftazidime) was 29.11% and 28.32%, respectively. For cefoperazone-sulbactam, resistant strains were found in 9.43%. Proportion of the strains resistant to aminoglycosides was 14.35% to netilmicin, 15.06% to amikacin, and 20.71% to gentamicin. The proportion of Klebsiella pneumoniae with high sensitivity to polyvalent bacteriophage was only 6.81%. Studied alcohol-based hand antiseptics were not effective at a 1:16 dilution in half of the experiments. Certain strains of Klebsiella pneumoniae were absolutely resistant to disinfectant, and persistent microorganisms forming dormant forms were also revealed.

Conclusion. The hospital population of Klebsiella pneumoniae was characterized by the predominant circulation of clonal line A which exhibited production of a wide ^-lactamase spectrum, demonstrated ampicillin and bacteriophage resistance, and frequently evolved into dormant forms.

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